The Science Fiction and Fantasy Writers of America (of which Glen Cook is a member) has four different holding libraries.  I believe they are all associated with university libraries, so the books are definitely out there for inter library loans.

I know this because I live by the University of New Brunswick, which is one of the holding centers.  As long as I'm nice to the librarians (i.e. can get access to the special collections) I have access to virtually SC&F novel published since 1970.

Richard